I have been taking lo estrin 24 fe since october 2010. The last two months I have had mid cycle bleeding, heavy enough to need a pantyliner and lasting on average 5-6 days with cramps. I had a baby 6 months ago, but my period was very regular after she was born and has been perfect until two months ago. I don't believe it is stress related, I was a lot more stressed the previous months and now I have been quite calm. What could this be?